In industrial installations it is necessary to switch a short pulse laser on and off during a processing process. In particular, this becomes necessary for example during the inscription or processing of workpieces. For this purpose, in general, it is necessary to trigger individual laser pulses or else it is necessary to call up a series of laser pulses having as far as possible constant or individually programmable pulse energy.
In the case of a continuously pumped amplifier system, the switching-on and -off process for setting laser pulses of predefined energy poses a problem. During the operating pulses, that is to say in phases of non-masked laser pulses of the seed laser oscillator, energy is stored in the active media of the amplifier systems. This stored energy leads to the energy of the first amplified laser pulses being greatly boosted if laser pulses from the seed laser oscillator rapidly pass through the amplifier again after the end of the operating pause, even though the laser pulses from the seed laser oscillator have a constant energy.
One currently known solution to the problem discussed provides for continuously operating the amplifier chain with a pulse train of fixed, settable repetition frequency, which leads to a pulse train comprising laser pulses of constant energy. These laser pulses are subsequently modulated or switched on and off by means of a suitable optical switch, in particular by means of an electro-optical or acousto-optical modulator (EOM, AOM).
The continuous operation of the short pulse laser disadvantageously leads to undesirable high operating costs.